Since polyethylene terephthalate (PET) has a high strength per weight and is inexpensive, it is used for a reinforcing member or the like of a tire for a multipurpose cord. When a cord composed of an organic fiber such as PET is used as a reinforcing member of a tire, generally, the cord is subjected to a dipping treatment by an adhesive agent such as a resorcin-formalin-latex (RFL)-based adhesive agent, then rubberized, and the obtained cord is applied to a tire as a rubber-cord complex. However, since there are few reaction active sites on the surface of polyester fiber such as PET due to its chemical structure, it has been difficult to ensure the adhesive strength between a filament and an adhesive agent in a step of combining the cord and the rubber.
As a technique for improving the adhesive property between PET and rubber, for example, Patent Document 1 discloses a two-bath treatment in which PET is dipped in an epoxy-based adhesive agent, and then in an RFL-based adhesive agent. A studies on the improvement of the epoxy-based adhesive agent is also conducted, and for example, Patent Document 2 discloses an epoxy-based adhesive agent composition comprising: a water-soluble polymer; and an aqueous urethane compound obtained by reacting organic polyisocyanates containing a structure in which aromatics are bonded by methylene with a compound having a plurality of active hydrogen atoms and a thermally dissociating blocking agent.
Here, by a two-bath treatment proposed in the above-mentioned Patent Document 1 and an epoxy-based adhesive agent composition proposed in Patent Document 2, the adhesive property between PET and rubber can be improved. However, since, when a tire is used under a high-speed environment and a high-load environment, a more rigid adhesive property between a polyester fiber and a rubber under an input of a dynamic strain, in particular, a heat resistant adhesive property is demanded, the establishment of a new technique has been expected.
Conventionally, when a high-speed durability performance test is performed in a state in which a camber angle is provided, on a tire in which a polyester fiber is applied to a carcass ply, in particular, on a tire for automobile, a separation of a carcass ply may occur at the tire side portion, leading to a failure of a tire at an early stage. This is because the adhesive strength between a polyester fiber and a rubber is insufficient.
By a two-bath treatment proposed in the above-mentioned Patent Document 1 and an epoxy-based adhesive agent composition proposed in Patent Document 2, the adhesive property between PET and rubber can be improved. However, since the adhesive property is insufficient when a tire is used under a high-speed environment and a high-load environment, it has been demanded that a more rigid adhesive property between a polyester fiber and a rubber under an input of a dynamic strain is attained, and that a tire whose high-speed durability performance is improved is attained.
Further, conventionally, in a run-flat tire in which a polyester fiber is applied to a carcass ply, a separation failure of a carcass ply may occur at the tire side portion during run-flat travering, leading to a failure of a tire at an early stage. This is because the adhesive strength between a polyester fiber and a rubber is insufficient.
By a two-bath treatment proposed in the above-mentioned Patent Document 1 and an epoxy-based adhesive agent composition proposed in Patent Document 2, the adhesive property between PET and rubber can be improved. However, since the adhesive property is insufficient when a tire is used under a high-speed environment and a high-load environment, it has been demanded that a more rigid adhesive property between a polyester fiber and a rubber under an input of a dynamic strain is attained, and that a run-flat tire whose run-flat durability performance is improved is attained.
Still further, conventionally, as one method of improving the run-flat durability of a run-flat tire, a method in which a reinforcing cord layer is applied from a shoulder portion to a side portion of a tread is proposed. However, when a polyester fiber is used for cord material of the reinforcing cord layer, a separation failure of a reinforcing cord may occur during run-flat traveling, leading to a failure of a tire at an early stage. This is because the adhesive strength between a polyester fiber and a rubber is insufficient.
By a two-bath treatment proposed in the above-mentioned Patent Document 1 and an epoxy-based adhesive agent composition proposed in Patent Document 2, the adhesive property between PET and rubber can be improved. However, since the adhesive property is insufficient when a tire is used under a high-speed environment and a high-load environment, it has been demanded that a more rigid adhesive property between a polyester fiber and a rubber under an input of a dynamic strain is attained, and that a run-flat tire whose run-flat durability performance is improved is attained.